MultiChain Developer Q&A - Recent questions tagged java

Java Client examples in developer's guide

Tue, 18 Jan 2022 03:55:17 +0000

I am trying to follow the developers guide to connect multichain via java client. There are 2 examples given (please check snapshot in below first link). "MultiChainJavaAPI" does not have main class while other "Multichain Client Java" (part-2) is giving 'connection refused' (see second link below). Plz hep?.

https://drive.google.com/file/d/1aBS6D1vdtWXPWJuBU2dOkbkRuJcv3L1m/view?usp=sharing

https://drive.google.com/file/d/1SZscLaVihiaqvDzwq-nLIMiVR1kqJpKI/view?usp=sharing

Why does command "CommandElt.GETPEERINFO" in MultiChainJavaAPI always return null?

Mon, 06 Jan 2020 07:57:00 +0000

I have two Multichain instances up and running in two different machine nodes. And, second node (it is virtual machine) is connected to the first one. I am developing a Java Application using MultiChainJavaApi in Eclipse IDE. The problem is that, I am able to run "getpeerinfo" command using command line, but the same command always returns null when I use MultiChainJavaApi command <CommandElt.GETPEERINFO> in an application.

Please find below code snippet

Object connectedNodes = null;
connectedNodes = commandManager.invoke(CommandElt.GETPEERINFO);

The below code snippet is a commandManager configuration

@Bean
public CommandManager commandManager() {
return new CommandManager("localhost", "9556", "multichainrpc","4sjwH****************************");
}

Any solution and suggestion is highly appreciated.

Multichain client for java failed to respond

Thu, 02 Aug 2018 08:02:49 +0000

Hi,

I'm trying to use the multichain client for java by Karavasilis Giannis you've recently twitted in July, but I've got a problem of "failed to respond" when calling functions of the class Example.

Here's the link of the java client im talking about.

I checked if address, port, rpcuser and rpcpassword was correct, and it is. I thought it could be a problem of non-local connexion to rpc, so I added the line "nrpcallowip=192.168.44.0/24" in multichain.conf of my blockchain. Still not working.

Do you have any suggestions for me ?

Thanks in advance for your time

I have BitcoinWallet Compilation error : Exception during program initialization

Mon, 05 Feb 2018 11:31:11 +0000

Hello,

I have a problem with the executable bitcoinWallet-3.0.1.jar:

Exception during program initialization

java.lang.NullPointerException

java.util.Hashtable.put(Hashtable.java:460

java.util.Properties.setProperty(Properties.java:166)

java.lang.System.setProperty(System.java:796)

org.ScripterRon.BitcoinWallet.Main.main(Main.java:125)

I'v got these lib files:

BitcoinCore-3.1.0.jar

bcprov-jdk15on-1.51.jar

bcprov-jdk15on-1.57.jar

slf4j-api-1.7.7.jar

h2-1.4.185.jar

slf4j-jdk14-1.7.7.jar

junit-4.11.jar

hamcrest-core-1.3.jar

Can you show me the way please ?

Thank you.

F.B.

Do you have a Demo written in Java?

Mon, 14 Aug 2017 01:44:51 +0000

Dear all

I find there are 2 demos which written in PHP and python, but I am familiar with java , do you have some demo written in Java?

Thanks a lot.

Issue getting JSON-RPC response using Java client

Sun, 09 Jul 2017 00:12:05 +0000

So I am trying to write a Java client that can communicate to the multichain server. The server is running on an Ubuntu VM (VM1) and I am writing my code on another Ubuntu VM (VM2).

Both VMs are on the same network and can communicate with one another. I can run multichain-cli commands from VM2 and get a successful response.

i was following the example from http://www.multichain.com/qa/2331/help-connection-to-mutlichain-using-java-client and I have the following code;

public JSONObject invokeRPC(String id, String method, List<Object> params, String chainName){
    HttpClient httpClient = HttpClientBuilder.create().build();
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("id", id);
    jsonObject.put("method", method);
    if(params != null && params.size() != 0){
        jsonObject.put("params", params);
    }
    jsonObject.put("chain_name", chainName);
    JSONObject responseJSONObject = new JSONObject();
    try{
        CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(
                new AuthScope("192.168.1.6", 9732),
                new UsernamePasswordCredentials("multichainrpc", "EZikv3MtoKA2yjrG6T7eTkPZMXntwr9k1ft7ja3jLLaA")
        );
        StringEntity myEntity = new StringEntity(jsonObject.toString());

        HttpPost httpPost = new

HttpPost("http://192.168.1.6:9732");       //HttpPost("http://multichainrpc:EZikv3MtoKA2yjrG6T7eTkPZMXntwr9k1ft7ja3jLLaA@192.168.1.6:9732");
        httpPost.setEntity(myEntity);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();

        System.out.println("------------------");
        System.out.println(httpResponse.getStatusLine());

        if(httpEntity != null){
            System.out.println("Response content length: " + httpEntity.getContentLength());
        }

        responseJSONObject = new JSONObject().getJSONObject(EntityUtils.toString(httpEntity));

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        httpClient.getConnectionManager().shutdown();
    }

    return responseJSONObject;
}

The code fails at 'HttpResponse httpResponse = httpClient.execute(httpPost);' with the following Exception;

org.apache.http.conn.HttpHostConnectException: Connect to 192.168.1.6:9732 [/192.168.1.6] failed: Connection refused (Connection refused)

at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:158)

at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:353)

at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:380)

at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236)

at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)

at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)

at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)

at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)

at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:55)

at com.recordz.general.connect.Connect.invokeRPC(Connect.java:52)

at com.recordz.general.connect.Connect.main(Connect.java:28)

Caused by: java.net.ConnectException: Connection refused (Connection refused)

at java.net.PlainSocketImpl.socketConnect(Native Method)

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)

at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)

at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)

at java.net.Socket.connect(Socket.java:589)

at org.apache.http.conn.socket.PlainConnectionSocketFactory.connectSocket(PlainConnectionSocketFactory.java:74)

at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:141)

... 12 more

I am not sure why this is happening as both VMs are on the same LAN and can communicate with one another.

Any advice would be much appreciated

Create MultiChain from a java component

Fri, 07 Jul 2017 12:44:13 +0000

Hi,

I am looking to work on a project where I primarily work in Java. I want to know tho is there way I can start up a multichain node using java?

I would like to have a nice frontend thats user friendly and allow the user to set their params for the node and click create and then the node is created.

Is this possible to do via Java?

I see theres solutions to communicate with a multichain node via rpc. At the moment I am not looking into that, I just want to see if it can be created. Once I know that if it can/can't I will then look into communicating with it.

Setting up MultiChainJavaAPI

Fri, 07 Jul 2017 07:06:27 +0000

Hi,

I am running a Java project where I want to incorporate MultiChain. I am trying to use MultiChainJavaAPI and I am not sure how I can include that in my original project as a dependency?

Should it even be included or should it run on its own?

Apologies if this question seems trivial to some, I am a complete noob to this

createrawsendfrom not running through Java Client...

Mon, 08 May 2017 13:52:34 +0000

Surprisingly, following command not running through Java Client, but running fine from CLI:

multichain-cli OPMApp createrawsendfrom 1LhxDQ8mQsJTVPUpCYnbeJTWgpSMq24qLQqxGi '{"1Msas1M6Mxx4W4bX2mkTrDp9y7WZmnCmzDCjdV":{"INR":50}}'

When I run it from java client, it raises following error:

Error parsing JSON:'{"1Msas1M6Mxx4W4bX2mkTrDp9y7WZmnCmzDCjdV":{"INR":50}}'

Following is the Java Client code snippet, I have implemented to run it:

StringBuffer cmdStr = new StringBuffer("multichain-cli ");

cmdStr.append(CHAIN).append(" ").append(command.toString().toLowerCase()).append(" ").append("1LhxDQ8mQsJTVPUpCYnbeJTWgpSMq24qLQqxGi ").append("'{").append('"').append("1Msas1M6Mxx4W4bX2mkTrDp9y7WZmnCmzDCjdV").append('"').append(":{").append('"').append("INR").append('"').append(":50").append("}}'");

pr = rt.exec(cmdStr.toString());

Any idea?

Java API

Wed, 26 Apr 2017 15:15:36 +0000

Hello Dear,
I would like to use the Java API of multichain.

When I try to call Issue method of IssueCommand class, it returns error "result:error: Error parsing JSON:source".

IssueCommand.issue("13KEZGKiAVBuT5LucrerES5bz892pmMxXa17ww", "Data source 2", 10000, 1);

I printed the command which runs on the server.

multichain-cli newchain issue "13KEZGKiAVBuT5LucrerES5bz892pmMxXa17ww" "Test 2 asset" 10000 1.0
command run

Could you tell what is the problem and how could I solve it?

Thank you so much.

Looking forward to hear something from you.

Tom,
Mobile: (1) 306-380-4386,

Email: uurtsaikh.nimonsystems@gmail.com

Attempting to connect to Multichain using a Java Client - Need help to resolve error.

Wed, 11 Jan 2017 07:30:43 +0000

Hi,

I am learning to use Multichain and tried sample code that I found to connect to Multichain blockchain. I am unable to connect and am receiving the error " The target server failed to respond ". The external IP address of server is 172.17.0.1 and port is 8333. Used the login credentials found in multichain.conf. Thanks in advance.

The code is as follows:

<----- Code Starts here ---->

package com.srs.multichain.json_rpc_client;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.ParseException;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

public class RPCClient {

    private static final String COMMAND_GET_BALANCE = "getbalance";
    private static final String COMMAND_GET_INFO = "getinfo";
    private static final String COMMAND_GET_NEW_ADDRESS = "getnewaddress";

    private JSONObject invokeRPC(String id, String method, List<String> params) {
        DefaultHttpClient httpclient = new DefaultHttpClient();

        JSONObject json = new JSONObject();
        json.put("id", id);
        //json.put("chain_name", chainName);
        json.put("method", method);
        if (null != params) {
            JSONArray array = new JSONArray();
            array.addAll(params);
            json.put("params", params);
        }
        JSONObject responseJsonObj = null;
        try {
            httpclient.getCredentialsProvider().setCredentials(new AuthScope("172.17.0.1", 8333),
                    new UsernamePasswordCredentials("multichainrpc", "FMHYwtrpoKRmUNySdXKCi8QFVNpvvAtqDxAvhfWw9DmK"));
            StringEntity myEntity = new StringEntity(json.toJSONString());
            System.out.println(json.toString());
            HttpPost httppost = new HttpPost("http://multichainrpc:FMHYwtrpoKRmUNySdXKCi8QFVNpvvAtqDxAvhfWw9DmK@172.17.0.1:8333");
            httppost.setEntity(myEntity);

            System.out.println("executing request" + httppost.getRequestLine());
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();

            System.out.println("----------------------------------------");
            System.out.println(response.getStatusLine());
            if (entity != null) {
                System.out.println("Response content length: " + entity.getContentLength());
                // System.out.println(EntityUtils.toString(entity));
            }
            JSONParser parser = new JSONParser();
            responseJsonObj = (JSONObject) parser.parse(EntityUtils.toString(entity));
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (org.json.simple.parser.ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            // When HttpClient instance is no longer needed,
            // shut down the connection manager to ensure
            // immediate deallocation of all system resources
            httpclient.getConnectionManager().shutdown();
        }
        return responseJsonObj;
    }

    public Double getBalance(String chainName, String account) {
        String[] params = { account };
        JSONObject json = invokeRPC(UUID.randomUUID().toString(), COMMAND_GET_BALANCE, Arrays.asList(params));
        return (Double)json.get("result");
    }

    public String getNewAddress(String chainName, String account) {
        String[] params = { account };
        JSONObject json = invokeRPC(UUID.randomUUID().toString(), COMMAND_GET_NEW_ADDRESS, Arrays.asList(params));
        return (String)json.get("result");
    }

    public JSONObject getInfo(String chainName) {
        JSONObject json = invokeRPC(UUID.randomUUID().toString(), COMMAND_GET_INFO, null);
        return (JSONObject)json.get("result");
    }
}

<----- Code snippet ends here ----->

I am receiving the following error -

{"method":"getinfo","id":"ddfe284b-d2af-4ea7-913e-26611729099e"}
executing requestPOST http://multichainrpc:FMHYwtrpoKRmUNySdXKCi8QFVNpvvAtqDxAvhfWw9DmK@172.17.0.1:8333 HTTP/1.1
org.apache.http.NoHttpResponseException: The target server failed to respond
    at org.apache.http.impl.conn.DefaultResponseParser.parseHead(DefaultResponseParser.java:101)
    at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:252)
    at org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:281)
    at org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:247)
    at org.apache.http.impl.conn.AbstractClientConnAdapter.receiveResponseHeader(AbstractClientConnAdapter.java:219)
    at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:298)
    at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:125)
    at org.apache.http.impl.client.DefaultRequestDirector.tryExecute(DefaultRequestDirector.java:633)
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:454)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:820)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:754)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:732)
    at com.srs.multichain.json_rpc_client.RPCClient.invokeRPC(RPCClient.java:50)
    at com.srs.multichain.json_rpc_client.RPCClient.getInfo(RPCClient.java:95)
    at com.srs.multichain.json_rpc_client.App.main(App.java:14)
Exception in thread "main" java.lang.NullPointerException
    at com.srs.multichain.json_rpc_client.RPCClient.getInfo(RPCClient.java:96)
    at com.srs.multichain.json_rpc_client.App.main(App.java:14)

<-------------- End of stacktrace ---------------->

Thanks,

Ramas.

How do I connect to a multichain I set up, using JSoup?

Tue, 10 Jan 2017 15:07:11 +0000

I have the following method, which maps parameters to a JSON String:

private static String encode(Map<String, String> params)
        {
            String retval = "";
            for(Entry<String,String> en : params.entrySet())
            {
                retval += (retval.isEmpty() ? "" : ", ") + "\"" + en.getKey() + "\" : \"" + en.getValue() + "\"";
            }
            retval += ", \"jsonrpc\" : \"1.0\"";
            retval += ", \"params\" : []";
            return "{" + retval + "}";
        }

And then this method to get the information from the blockchain

public static void getBlockChainParams() throws IOException
   {
   // params
   String server = "192.168.0.0";
   String port = "0000";
   String chainName = "iTextChain";

   // json
   Map<String,String> params = new HashMap<>();
   params.put("method", "getinfo");
   params.put("id", "1");
   params.put("chain_name", chainName);

   String jsonData = encode(params);
   System.out.println(jsonData);

   // build request
   String url = "http://" + server + ":" + port;
   System.out.println(url);
   Document doc = Jsoup.connect(url)
       .ignoreContentType(true)
       .ignoreHttpErrors(true)
   .header("Accept", "application/json")
   //.header("Accept-Encoding", "gzip,deflate,sdch")
   //.header("Accept-Language", "en-EN,es;q=0.8")
   .header("Connection", "keep-alive")
   //.header("X-Requested-With", "XMLHttpRequest")
   .data(jsonData, "")
   .post();

   // send
   System.out.println(doc.toString());
   }

This code keeps throwing SocketException however.
What am I doing wrong?

Help! Connection to Mutlichain using Java Client?

Tue, 02 Aug 2016 08:05:18 +0000

How am I able to connect to Multichain block running on another server using a Java client? Thanks for the help

HTTP 500 Error Using Java RPC

Thu, 24 Mar 2016 19:30:21 +0000

Hello all,

I am having an issue using RPC to create an asset.
My code is as follows to make the call:

public void testCreatingAsset(){

    ArrayList<Object> params = new ArrayList<>();
    params.add(address);
    params.add("asset1");
    params.add(1000);
    params.add(0.01);
    JSONObject creatingAssetObject = rpcClient.request("issue", params);
}

When the call is made I get the following error:

Server returned HTTP response code: 500 for URL

I have tried the following things to either solve or find the cause of the problem:

I have tried manually making the call (writing it in the command line) and the call is successful - returning the JSON object

Reversed ordering of params ArrayList (adding 0.01 first then 1000 etc...)

Tried making a different call, I tried "help" with an empty ArrayList and is successful, it returns the JSON object

I tried making a sendassettaddress call using RPC and this didn't work either, it seems any calls made with paramaters are failing

Thanks in advance,

GOMD

Connect to a node using raw JSON-RPC in Java

Thu, 18 Feb 2016 12:31:37 +0000

Is there a way to use any JSON-RPC framework in Java to connect and pass commands to a node?

I have tried this and I get a connection reset even though it connects just fine using telnet (so there's definitely a process attached to the port):

Map<String, String> headers = new HashMap<>();
headers.put("Authorization", "Basic <My credentials in Base64 from multichain.conf>");
JsonRpcHttpClient client = new JsonRpcHttpClient(new URL("http://<my node>:9551"), headers);
client.invoke("getinfo", new Object[] { "chain_name", "chain1", "id", 1 });

I am using

<dependency>
        <groupId>com.github.briandilley.jsonrpc4j</groupId>
        <artifactId>jsonrpc4j</artifactId>
        <version>1.2.0</version>
</dependency>

as JSON-RPC client. What am I doing wrong?

Trying to connect via Java Client

Tue, 12 Jan 2016 12:24:28 +0000

I'm trying to make a connection with the multichain through a java client.

I tried to use both API as show below however, both show connection error refused.
I'm trying to connect through a client on the server, I tried to run the .jar on own server and the error messages were the same.

I also tried to follow the orientations of the following topics with the same doubts, but had no success. Below as well as station I view the files and params.dat multichain.conf

http://www.multichain.com/qa/362/issue-while-connecting-with-node-using-java-client

http://www.multichain.com/qa/633/connect-multichain-using-json

In server multichain.conf: (ip client)

rpcuser=multichainrpc
rpcpassword=XYZ
server=1
rpcallowip=10.20.20.47/255.255.255.0
rpcport=4368

And params.dat

anyone-can-connect = true   # Anyone can connect. Ignored if public-network=true.
anyone-can-send = true   # Anyone can send.
anyone-can-receive = true   # Anyone can receive.

API BitcoinRPCClient

https://github.com/cdelargy/BitcoinRPCClient

RPCClient c = new RPCClient();
c.getInfo();

public class RPCClient {
private static final String COMMAND_GET_INFO = "getinfo";

private JSONObject invokeRPC(String id, String method, List<String> params) {
DefaultHttpClient httpclient = new DefaultHttpClient();

       JSONObject json = new JSONObject();
       json.put("id", id);
       json.put("method", method);
       if (null != params) {
           JSONArray array = new JSONArray();
           array.addAll(params);
           json.put("params", params);
       }
       JSONObject responseJsonObj = null;
       try {
           httpclient.getCredentialsProvider().setCredentials(new AuthScope("10.20.20.221", 4368),
                   new UsernamePasswordCredentials("multichainrpc", "XYZ"));
           StringEntity myEntity = new StringEntity(json.toJSONString());
           System.out.println(json.toString());
           HttpPost httppost = new HttpPost("http://10.20.20.221:4368");
           httppost.setEntity(myEntity);

           System.out.println("executing request" + httppost.getRequestLine());
           HttpResponse response = httpclient.execute(httppost);
           HttpEntity entity = response.getEntity();

           System.out.println(response.getStatusLine());
           if (entity != null) {
               System.out.println("Response content length: " + entity.getContentLength());
           }
           JSONParser parser = new JSONParser();
           responseJsonObj = (JSONObject) parser.parse(EntityUtils.toString(entity));

(... catch)
   }

   public JSONObject getInfo() {
       JSONObject json = invokeRPC(UUID.randomUUID().toString(), COMMAND_GET_INFO, null);
       return (JSONObject)json.get("result");
   }
}

ERROR:

API Bitcoin-JSON-RPC-Client

https://bitbucket.org/azazar/bitcoin-json-rpc-client/wiki/Home

public static void balance() throws BitcoinException {
System.out.println(new BitcoinJSONRPCClient().getBalance());
}

ERROR:

Java client library

Mon, 17 Aug 2015 12:20:20 +0000

Do you recommend a java client library for the JSONRPC API calls? I have been using the CLI, planning to switch to the API soon.